Income Tax - Summary of Tax (Charge)/Benefit Recognised in Other Comprehensive Income (Detail) - GBP (£) £ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Income tax relating to components of other comprehensive income [abstract] | |||
| Net exchange differences on translation of foreign operations | £ 0 | £ 2 | £ 0 |
| Fair value gains on other financial assets | 0 | 0 | 0 |
| Remeasurement of retirement benefit obligations | (3) | (2) | 20 |
| Tax benefit/(charge) recognised in other comprehensive income | £ (3) | £ 0 | £ 20 |
| X | ||||||||||
- Definition The amount of income tax relating to amounts recognised in other comprehensive income. [Refer: Other comprehensive income] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to exchange differences on the translation of financial statements of foreign operations. [Refer: Other comprehensive income; Reserve of exchange differences on translation] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to remeasurements of defined benefit plans. [Refer: Other comprehensive income; Reserve of remeasurements of defined benefit plans; Defined benefit plans [domain]] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Income tax relating to fair value gain on other financial assets of other comprehensive income No definition available.
|